Comparison of commercial peanut skin test extracts

Abstract

Background: Skin prick testing is a major tool for diagnosing food allergy. Food allergen extracts have not been standardized; this may lead to great variability in the predictive accuracy of skin prick tests. Methods: Six commercial peanut skin test extracts were compared in vitro with RAST inhibition assays, ELISA, and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting with sera from peanut-allergic adults and in vivo by skin prick testing. Results: ELISA showed that the content of peanut allergens Ara h I and Ara h II in the extracts ranged from 0.0015 to 0.0236 and 0.0001 to 0.0164 mg Eq/ml, respectively. RAST inhibition studies showed that the extracts produced curves of similar slope, suggesting conservation of allergenic epitopes. SDS-PAGE revealed differences in protein profiles because roasted extracts generally possessed the same number and proportion of major protein bands but raw extracts varied more in both respects. SDS-PAGE and immunoblotting showed that two of the extracts contained major IgE-binding protein bands that did not appear in the others. One roasted extract gave little protein banding and consequently little IgE binding. Conclusions: Skin testing results showed no differences in the ability of the extracts to provoke a positive skin test response in peanut-sensitive subjects. (J A LLERGY C LIN I MMUNOL 1995;95:837-42.)